Models of Memory

Introduction to Cognitive Science Lecture 7: Memory/Sleep September 29, 2009

Lecture Overview

• The Modal Model (Atkinson & Shiffrin)• ACT* Model (Anderson)• Working Memory Model (Baddeley)• Change Blindness• The Hippocampus• Sleep & Memory

MODELS OF MEMORY

RETRIEVAL

Short-term Memory

Long-term Memory

Sensory Memory

STIMULUS INPUT

The Modal Model (Atkinson & Shiffrin)

Figure 5.3, p 134 in text

RESPONSE OUTPUT

ENCODING

e.g. Visual (iconic)Auditory (echoic), etc.

Some Control Processes: Rehearsal, Coding, Decisions, Retrieval Strategies

ACT* Model: Adaptive Control of Thought (Anderson)

Working Memory

DeclarativeMemory

Production Memory

External Environment

Encoding Performance

Storage Match

ExecutionRetrieval

Figure 5.4, p 136 in text

The Working Memory Model (Baddeley)

Visuo-spatial Sketchpad

Processing of Visual Information

Executive Control System

Supervises and controls processes

Articulatory Loop

Rehearsal and processing of auditory information

Figure 5.5, p 138 in text

Occurs when major changes to a visual scene go unnoticed by the observer.

TESTING THE CAPACITY OF VISUAL WORKING MEMORY:

CHANGE BLINDNESS

Pay Attention….

Change Blindness

Differences between the two images can be detected only if we attend to one of the changing objects.This experiment demonstrates that we memorize only very little information from visual scenes.We typically use visual scenes as our “external memory” rather than filling our working memory with a large amount of scene information.

The Hippocampus

Long-Term Memory LearningNavigation

THE HIPPOCAMPUS =Dentate Gyrus, CA1-CA3, & Subiculum

Marjor input from Entorhinal Cortex which is other brain areas such as the Prefrontal Cortex

Information Flow:Entorhinal Cortex Dentate Gyrus CA3CA1 Subiculum

Neurogenesis: birth of new neurons

Highly active throughout development

Also adult hippocampal neurogenesis (dentate gyrus)!

What might this mean for learning and memory?

Hippocampal Damage

• Retrograde Amnesia: loss of memories before damage to the hippocampus

• Anterograde Amnesia: inability to form new memories

• Some causes: aging, Alzheimer’s disease, stress, temporal lobe epilepsy

Patient H.M.Patient H.M.

http://images.google.com/imgres?imgurl=http://dspace.mit.edu/bitstream/handle/1721.1/45580/9-10Spring-2004/NR/rdonlyres/Brain-and-Cognitive-Sciences/9-10Spring-2004/8AFEA93F-9C52-42E5-B967-211CCD2AA287/0/chp_9_10_hip_enc.jpg&imgrefurl=http://dspace.mit.edu/bitstream/handle/1721.1/45580/9-10Spring-2004/OcwWeb/Brain-and-Cognitive-Sciences/9-10Spring-2004/CourseHome/index.htm&usg=__baapQ1i44dpgT7ZDQuuBuOVnwnw=&h=307&w=350&sz=26&hl=en&start=2&um=1&tbnid=n5pajUYXebb7tM:&tbnh=105&tbnw=120&prev=/images%3Fq%3Dcoronal%2Bhippocampal%2Bhuman%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG%26um%3D1

Anterograde Amnesia:Intact working and procedural memoryCould not commit to long-term

SOME Retrograde Amnesia:Couldn’t remember 3–4 -day prior to surgery, + some events up > 11 years prior

Able to commit new motor skills to long-term memory without actually remembering learning them

After Surgery for Temporal Lobe Epilepsy

Sleep & Memory Consolidation

• Born & Marshall The contribution of sleep to hippocampus-dependent memory consolidation

• MP Walker• Stickgold

Matthew P. Walker* and Robert Stickgold* Sleep-Dependent Learningand Memory Consolidation Neuron, Vol. 44, 121–133, Sept 30, 2004

Relaxed Wakefulness

NREM Stage 1

NREM Stage 2

NREM Stage 3, 4/Slow Wave SleepDelta Waves

REM

Sleep Can Be Divided Into:

•NREM (Stages 1-4)

•REM

Different stages are identified using EEG

SLEEP: Overview

NREM & REM cycle about every 90 minutes

Early in the night: NREM 3 & 4 dominate

Later in the night: Stage 2 and REM dominate

Neurobiology of Sleep Regulation

Many subcortical regions are involved:•Thalamus•Hypothalamus•Pons

Dreaming also involves:•Cortical: Prefrontal and Posterior (vision)•Subcortical: limbic (emotion)

Some key neurotransmitters:•Serotonin (5-HT) •Noradrenaline (NA)•Acetylcholine (Ach)

3, 679-693 (September 2002) Hobson & Pace-Schott

Influence of sleep on a motor skill task (A-C) and a visual skill task (D-F)

(A)Motor performance increase after sleep

(B) Such performance increase is not strengthened during subsequent wake phase

(C) Performance improve is strongly correlated with amount of stage 2 NREM sleep.

(D) Increased level of visual performance after one night of sleep.

(E) Performance iprovement with regular sleep periods (red) and no improvement after sleep deprivation during first night after training (green).

(F) Improvement is correlated with amount of slow-wave sleep and REM sleep.

Replay of hippocampal firing during sleep

Rodent Running path

Hippocampal cells and location-specific firing during running

Timecourse of firing patterns of 10 cells (rows) during running

Timecourse of firing patterns of 10 cells (rows) during REM

Louie & Wilson. Temporally Structured Replay of Awake Hippocampal Ensemble Activity during Rapid Eye Movement Sleep . Volume 29, Issue 1, January 2001, Pages 145-156